Gamerscore for atleast 3 of my games had mysteriously been reduced to zero (other games are unaffected however). These games include COD Black Ops, AC II and AC Brotherhood. The problem first started when I downloaded my gamertag onto my new xbox 360. Although I can still play the saved game data for all these 3 games as well as gain new achievements; I can never see my old achievements. What's even more strange is that my old achievements still appear on my old xbox even though they don't show up on my new xbox nor the activity feed on xbox.com
I reported this problem to microsoft support and they came up with a few possible solutions, but none of their suggestions actually worked out. I tried clearing the cache and I also tried deleting and redownloading my gamertag. Microsoft also suspected that saved game data got corrupted as I transferred it from one xbox to another. But since my old achievements don't appear even though i did unlock new achievements; they seemed to rule out this possibility. I also tried contacting Ubisoft about this but they were no better either.
If there's anybody out there who can help, please do! Your help will be greatly appreciated!!